The 3M 2500 Series Filtrete 1" Filter is a pleated air filter with a MERV rating of 4, designed for indoor air quality improvement. This filter is made with fiberglass filter media and electrostatic filtration technology, providing efficient filtration for up to 3 months. The filter comes in a pack of 4, each measuring 1 inch in height, diameter, and width, ensuring a perfect fit for your heating, cooling, or air system. With a paper filter frame material, this filter offers reliable and effective filtration for a clean and healthy indoor environment.